The present invention relates to flow control devices and particularly to such devices as used in drip irrigation emitters.
The invention is particularly applicable to the tube-type drip irrigation emitter, which includes a tube for conducting water therethrough and formed with a plurality of discharge openings spaced along the length of the tube, and a plurality of flow control units bonded to the inner face of the tube at spaced intervals along the length of the tube. Such flow control units are applied to the tube at the time the tube is extruded and while the tube is still soft so that the flow control unit is firmly bonded to the inner face of the tube. Each flow control unit includes an inlet communicating with the interior of the tube, an outlet communicating with one of the discharge openings, and a flow control passageway connecting the inlet to the outlet. In the pressure-compensated type emitter, the flow control passageway includes an elastomeric membrane which controls the flow through the passageway in response to the differential pressure on the opposite faces of the membrane, thereby maintaining a substantially uniform discharge rate despite variations in the inlet pressure.
My patent application Ser. No. 08/389,479 discloses a drip irrigation emitter of this type including a housing constructed of a body member and a cover securing between them the pressure-compensating membrane. In the described embodiment, the cover is formed with a plurality of inlet openings in the form of slits defining filtering passageways through which the water is inletted into the housing.